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BELL SYSTEM TECHNICAL JOURNAL 



The sixth network, shown in Fig. 1 1 , is structurally more elaborate than 

 any which have preceded it. Its design equations are also relatively 



2^0' 



k — VA 



Z2. 





_, ^^ ,^>^y^ 



2Ro 



a'Zsi 



2^21 



6-^ = 1 + ^ 



m 



:iRo 



Ro 



pQo 



=[-^r 



^11 ^21 ~ Ro 



26 



1.5 2.0 



UJ 



Wo 



3.5 



Fig. 11 — A variable equalizer with zero loss at one frequency for all settings 

 of the controlling element. 



elaborate and difficult to deal with. It possesses, however, the salient 

 property that when Zn = 0, perfect transmission of power from one 

 terminating impedance to the other is secured at any setting of the 

 variable resistance. This property suggests that the network may be 



